a). Field of the Invention
This invention relates to a semiconductor device, in particular of type having a mount which is certainly secured on a circuit board to support a semiconductor element on the mount.
b). Description of the prior art
A known semiconductor device includes a circuit board on which a mount made of copper is secured to support a semiconductor element thereon. The mount is effective to outwardly radiate heat produced by the semiconductor element upon operation for increase of electric current capacity.
However, the mount tends to be attached on the circuit board in the slant condition because of irregular amount of brazing metal between a flat surface of the mount and the circuit board. In addition, it is very difficult to secure the mount on the circuit board in an exactly upright condition with uniform thickness of the brazing metal all over the flat surface of the mount. Moreover, it is also actually impossible to braze a plurality of mounts on the circuit board with a constant thickness of brazing metal for a same level although the mounts are correctly secured on the circuit board in the upright condition.
In case the mount is secured on the circuit board in the inclined condition, a semiconductor element cannot correctly be attached on the mount by die bonding, and ends of thin wires cannot be connected on electrodes of the semiconductor element, thereby resulting in failure of connection or disconnection of the thin wires. Also, uneven or insufficient thickness of the brazing metal causes incorrect electric properties or deterioration of the semiconductor device in an environment test such as severe thermal test or thermal fatigue test, and sometimes the slant attachment of the mount would give rise to some troubles in the manufacturing process of the semiconductor device.
An object of the present invention is to provide a semiconductor device capable of avoiding slant attachment of a mount on a circuit board.
Another object of the invention is to provide a semiconductor device which has a mount certainly secured on a circuit board correctly in the upright condition.